// cookie
// 读取cookie函数
function getCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}
// 存储cookie
function setCookieWithExpiration(name, value, daysUntilExpire) {
    var date = new Date();
    date.setTime(date.getTime() + (daysUntilExpire * 24 * 60 * 60 * 1000));
    var expires = "expires=" + date.toUTCString();
    document.cookie = name + "=" + value + ";" + expires + ";path=/";
}